As everyone knows, there have been very few significant innovations in the ship-building sector over the last few decades.
Actually, ordinary merchant and naval watercrafts are being built on the basis of long known ship-building techniques. Among these techniques, the most important (and popular) ones--concerning quickwork--include the use of the V-shaped bow, bottom with a developed keel, rudder and propeller.
All the above-mentioned parts have been remarkably improved on pleasure- and racing-watercrafts, whereas very few steps forward have been made with regard to merchant crafts.
The use of the V-shaped bow, that allows the ship to plough the waters and the bottom to enter the hollow just created, is still up-to-date; the researches carried out to improve its shape have resulted in fair improvements. However, it is worth recalling that over the last few years the use of a bulb applied on the bow, immediately below sea level, has contributed to reduce wave resistance in medium and high tonnage ships.
A further technical amelioration, regarded as essential today, is the use of a bottom with a developed keel, in order to reduce roll and pitch especially during sea storms.
The use of a propeller for the craft propulsion is another widespread achievement in the ship-building sector.
This propelling unit has been thoroughly studied for several years; remarkable improvements have been made to its shape, blades' features and overall structure. Attempts have also been made to improve the overall efficiency of the propeller as much as possible (according to its bottom shape), but rarely has it exceeded 60-70%.
Finally, the use of the helm unit must be regarded as a vital accomplishment in order to manoeuvre the watercraft. This unit has undergone a progressive--yet slow--technical evolution, since its effect in slowing down the ship motion is well established and therefore does not require too many improvements. In spite of the continuous progress in designing, propelling and improving techniques, the results so far obtained cannot be compared to those achieved in the sectors of land and air vehicles, where new technological innovations have remarkably increased their speed and manoeuvrability and simultaneously reduced their operating costs. Indeed, the use of V-shaped bows and current hull shapes on merchant ships has not yet enabled these ships to overcome the wave resistance opposing their heading at high speeds--unless their bearing structures have been remarkably reinforced. However, this stiffening solution would bring about considerably higher building costs and, above all, higher operating costs, since fuel consumption increases dramatically.
Moreover, during navigation, the use of propeller and helm units causes a great waste of energy, which is proportional to the ship speed.
As already mentioned, the propeller efficiency is unlikely to exceed 70% and the use of helm in each sheer causes cavitation and braking, thus resulting in an increase in fuel consumption in order to keep the ship speed constant.
It should also be stressed that even a highly developed keel and the propeller and helm fastenings are likely to cause a waste of energy due to their frictional resistance during navigation.